struct nouveau_subdev base;
 
        u64 limit;
+       u8  dma_bits;
        u32 pgt_bits;
        u8  spg_shift;
        u8  lpg_shift;
 
 
        priv->base.create = nv04_vm_create;
        priv->base.limit = NV04_PDMA_SIZE;
+       priv->base.dma_bits = 32;
        priv->base.pgt_bits = 32 - 12;
        priv->base.spg_shift = 12;
        priv->base.lpg_shift = 12;
 
 
        priv->base.create = nv04_vm_create;
        priv->base.limit = NV41_GART_SIZE;
+       priv->base.dma_bits = 39;
        priv->base.pgt_bits = 32 - 12;
        priv->base.spg_shift = 12;
        priv->base.lpg_shift = 12;
 
 
        priv->base.create = nv04_vm_create;
        priv->base.limit = NV44_GART_SIZE;
+       priv->base.dma_bits = 39;
        priv->base.pgt_bits = 32 - 12;
        priv->base.spg_shift = 12;
        priv->base.lpg_shift = 12;
 
                return ret;
 
        priv->base.limit = 1ULL << 40;
+       priv->base.dma_bits = 40;
        priv->base.pgt_bits  = 29 - 12;
        priv->base.spg_shift = 12;
        priv->base.lpg_shift = 16;
 
                return ret;
 
        priv->base.limit = 1ULL << 40;
+       priv->base.dma_bits = 40;
        priv->base.pgt_bits  = 27 - 12;
        priv->base.spg_shift = 12;
        priv->base.lpg_shift = 17;
 
        u32 bits;
        int ret;
 
-       if (nv_device(drm->device)->card_type >= NV_50) {
-               if (pci_dma_supported(dev->pdev, DMA_BIT_MASK(40)))
-                       bits = 40;
-               else
-                       bits = 32;
-       } else {
+       bits = nouveau_vmmgr(drm->device)->dma_bits;
+       if ( drm->agp.stat == ENABLED ||
+           !pci_dma_supported(dev->pdev, DMA_BIT_MASK(bits)))
                bits = 32;
-       }
 
        ret = pci_set_dma_mask(dev->pdev, DMA_BIT_MASK(bits));
        if (ret)